A major earthquake measuring 7. 9 on the Richter scale struck the South Pacific island country of Tonga on Friday morning. There were no immediate reports of casualties or damages.

The quake, which occurred at 6:17 a.m. Tongan local time (1817 GMT Thursday), was centered some 210 km from the Tongan capital Nuku'alofa at a depth of 10 km, the New Zealand Institute of Geological and Nuclear Sciences (GNS) said.

A tsunami alert was issued after the earthquake, but has now been canceled.

The Pacific Tsunami Warning Center initially issued advisories for Tonga, Fiji, Nuie, Samoa, Wallis and Futuna and the Kermadec Islands.

The center said sea level readings indicate a tsunami was generated but its waves were not much higher than normal sea levels.

An undersea volcano erupted off Tonga earlier this week, 10 km off the main island, Tongatapu.

GNS said the volcano was erupting in two areas and the eruption may last up to a week.

Talita Tuitulotu, news editor of TV and Radio Tonga, told Xinhua on the phone that there was panic at the first stage but the situation has been back to normal in the Tongan capital.

"There was no sign of panic after the tsunami warning was canceled. People were back to work and school were not closed," she said, adding that there was no obvious sign of damage at this stage.

Director of the Met Office in Tonga Ofa Faanunu said the office has sent all the appropriate information to the right groups.

The Met Office has issued the warning for all of Tonga on National Radio, asking people to evacuate to higher ground.

Ofa Faanunu said so far there has been no reports of damage on the main island of Tongatapu.

Apai Moala, senior geological assistant with the Tongan Ministry of Land and Surveys, said there had been no reports from coastal areas of a wave.

Moala said Tongan authorities were therefore confident there had been no wave of any significance generated.

New Zealand's Ministry of Civil Defense and Emergency Management issued a tsunami warning shortly after 8:00 a.m. Friday, but canceled it about an hour later.

"As more information has become available it is now clear that there is no risk of a tsunami that could cause damage to New Zealand," said the ministry's director John Hamilton.

Editor: Yan